A solar power generator, an energy storage device, and the like may be connected to a power system and coordinated control may be performed with these devices serving as distributed power sources. Each of the distributed power sources is provided with a power electronics device (an inverter or a converter) that performs power conversion. It is assumed that a system automatically performs capacity change in any cases including expansion, occurrence of abnormality or the like by applying autonomous cooperative control among multiple power electronics devices while ensuring operational flexibility, wherein the power electronics devices are provided with a communication function. For example, it is assumed that a plurality of power electronics devices are connected in parallel to enable optimization of output, not as individual power electronics devices but as a power electronics system. In this case, it is necessary to determine a master device (hereinafter referred to as “master”) that acts as a controlling entity for coordinating the outputs of each of the power electronics devices. Power conversion efficiency as a system can be improved by determining the master from among the plurality of power electronics devices, determining the remaining devices as slave devices (hereinafter referred to as “slaves”), and causing the master to give instructions regarding the output power to the slaves.
However, when the roles of master/slaves are automatically determined between or among the plurality of power electronics devices at the time of initial installation, in the event of occurrence of abnormality, or the like, each power electronics device operates individually and independently. As a result, it is possible that the operation is started in a state where a plurality of masters exist in the system if the state of establishment or non-establishment of a logical configuration for power control is not taken into account.
In addition, when addition, stoppage, failure, and the like of power electronics devices constituting the distributed power supply system occur in a distributed power supply system where multiple power electronics devices configure a master-slave relationship and cooperatively operate, it is necessary to reconfigure the group without stopping the power output and restore the normal operation state.
Conventionally, a method is known according to which multiple inverters whose master/slave roles are specified in a fixed manner realize parallel operation that corresponds to phase synchronization control of output power using an optical communication line. In addition, a method is known according to which the device information is notified to a server that monitors and controls the devices when the devices are connected to the system, using a communication function, and setting of the software on the server is automatically done. However, even when these methods are combined, it is not possible to solve the aforementioned problem.